The present invention generally relates to orthopedic implants, and, more particularly, to spinal fusion devices.
When a spinal disc deteriorates one method of treatment is a spinal fusion procedure. Spinal fusion typically involves fusion between two adjacent vertebrae by removing a disc between two adjacent vertebrae and placing a graft material or fusion mass between the vertebrae. The disc includes an annulus which surrounds a nucleus. Surgical access to the disc may be from the anterior or posterior sides (stomach and back) of the patient. The disc is removed from between the two adjacent vertebrae by removing at least a part of the annulus as well as the softer nucleus. A cage is placed between the vertebrae where the disc is removed and a fusion graft or graft mass is packed within the cage and extends between the end plates of the adjacent vertebrae. Rods may also be placed on the posterior side of the spine, with screws attached to a respective rod and extending into a respective vertebrae to stabilize the fusion.
A number of alternative devices for spinal disc treatment are reported.
One alternative device includes rigid, three-dimensional geometric solid devices, either impervious or porous, that function as support struts. When placed in the area of the disc between adjacent vertebral bodies, they allow and/or encourage bone to grow through and/or around the device to cause a bony fusion between two adjacent vertebral bodies. Examples of such devices are reported in U.S. Pat. No. 6,015,436 to Schonhoffer, U.S. Pat. No. 6,010,502 to Bagby, U.S. Pat. No. 5,972,031 to Biedemmann et al., U.S. Pat. No. 5,895,427 to Kuslich, U.S. Pat. No. 5,735,899 to Schwartz et al., U.S. Pat. No. 5,720,748 to Kuslich, U.S. Pat. No. 5,709,683 to Bagby, U.S. Pat. No. 5,700,291 to Kuslich, U.S. Pat. No. 5,669,909 to Zdeblick, U.S. Pat. No. 5,514,180 to Heggeness et al., U.S. Pat. No. 5,591,235 to Kuslich, U.S. Pat. No. 5,489,308 to Kuslich, U.S. Pat. No. 5,489,307 to Kuslich, U.S. Pat. No. 5,405,391 to Henderson et al., U.S. Pat. No. 5,263,953 to Bagby, U.S. Pat. No. 5,059,193 to Kuslich, U.S. Pat. No. 5,015,255 to Kuslich, U.S. Pat. No. 5,015,247 to Michelson, U.S. Pat. No. 4,946,458 to Harms et al., U.S. Pat. No. 4,936,848 to Bagby, U.S. Pat. No. 4,834,757 to Bantigan, U.S. Pat. No. 4,820,305 to Harms et al., U.S. Pat. No. 4,501,269 to Bagby, and U.S. Pat. No. 4,401,112 to Rezaian.
Another alternative device includes semi-rigid artificial joints that allow motion in one or more planes. Examples of these device are reported in U.S. Pat. No. 4,759,769 to Kostuik, U.S. Pat. No. 6,039,763 to Shelokov, and commercially available examples such as the Link device or Charite Intervertebral Disc Endoprosthesis.
Still another alternative device includes non-rigid cushions designed to replace the nucleus of the disc. Examples of artificial discs are described in U.S. Pat. No. 4,904,260 to Ray, U.S. Pat. No. 4,772,287 to Ray and U.S. Pat. No. 5,192,326 to Boa.
Yet another alternative device includes flexible, expandable bags or balloons that become rigid when injected with materials that can support loads. Examples are reported in U.S. Pat. No. 5,571,189 to Kuslich, U.S. Pat. No. 5,549,679 to Kuslich and U.S. Pat. No. 6,332,894.